So although the neighborhood is not one of the "walkable" ones in Palo Alto, it has this major amenity three steps away.
I would take a great, upscale gym and outdoor pool over a Starbucks next door, any day. I don't have kids but if I did, day care would be a big plus.
Altaire is paying for the first year membership, too.
I just sold a condo in Echelon, and we looked at Altaire and Sterling Park as well. All suffer from not being in a good walkable area to restaurants or shops. My client decided on Echelon because it felt less like an apartment than Altaire, and she preferred having her own garage. Echelon is a quieter location than the other two.
I'd recommend visiting all three and buying where you feel the most at home, and which you like the best. Since you are planning to live there for 5 years, you had better like it! We can't forecast appreciation, but based on how similar homes have appreciated relative to each other, I don't foresee significant differences in appreciation between these developments.
Both are located in roughly the same area of Palo Alto with Echelon appearing to be slightly smaller and more upscale. Here is a case where you would want to go and visit them both - not too difficult because they are close to each other.
Anything with a Palo Alto address will be desirable come resale time. Palo Alto has, in addition to great weather, good schools and a family oriented community. Life-styles in the San Francisco Bay Area are many, relative to the community and or the neighborhoods. It is likely that both of the condo's will inherit and or retain the community feel, likely the same schools, etc. - it may come down to the quality of construction, floor plans and amenities. If you want I would be happy to show them to you, otherwise, it's more a matter of appeal. Which one do you like better?